Sector scanning ultrasonic inspection apparatus

ABSTRACT

This is an ultrasonic transducer scanning support system comprising at least three arms serially joined in pivotal relation one to the other and to a base. Three position transponders are mounted on the base with each of the pivoted arms operatively coupled to a transponder whereby signals are developed representative of the position of a transducer mounted on the end of the third arm which control the origin of an indicating means to correspond to the position of the transducer.

United States Patent [191 Meyer et al.

[451 Dec. 9, 1975 SECTOR SCANNING ULTRASONIC INSPECTION APPARATUS [75]Inventors: Edward P. Meyer, Boulder; William L. Wright, Longmont, bothof C010.

[73] Assignee: Picker Electronics, Inc., Longmont,

[22] Filed: Aug. 7, 1970 [21] Appl. No.: 62,143

Related US. Application Data [63] Continuation of Ser. No. 801,882, Oct.1, 1969, abandoned, which is a continuation-in-part of Ser. No. 373,312,June 8, 1964, abandoned.

[52] US. Cl. 73/67.8 S

[51] Int. Cl. GOIN 29/04 [58] Field of Search 73/67.767.9, 73/71 .5

[56] References Cited UNITED STATES PATENTS 3,086,390 4/1963 Brown73/67.8

3,257,843 6/1966 Cowan 73/7l.5

3,308,652 3/1967 Appel et al. 73/67.8 X

OTHER PUBLICATIONS Buchanan et al., Ultrasonic Flaw Plotting Equipment-A New Concept for Industrial Inspection, NonDestructive Testing,Sept.-Oct. 1955, pp. l725. Buchanan et al., Watertown Arsenal LabratoryReport No. WAL 143/28, July 1955, pp. 1 & 12-16.

Primary ExaminerRichard C. Queisser Assistant ExaminerJohn P. BeauchampAttorney, Agent, or FirmWatts, Hoffmann, Fisher & I-Ieinke Co.

[ ABSTRACT This is an ultrasonic transducer scanning support systemcomprising at least three arms serially joined in pivotal relation oneto the other and to a base. Three position transponders are mounted onthe base with each of the pivoted arms operatively coupled to atransponder whereby signals are developed representative of the positionof a transducer mounted on the end of the third arm which control theorigin of an indicating means to correspond to the position of thetransducer.

15 Claims, 13 Drawing Figures US. Patent Dec. 9 1975 Sheet 1 of 43,924,452

INVENTORS RD P AM ATTORNEYS Dec. 9 1975 Sheet 2 0f 4 3,924,452

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U.S. Patent 3 ww Q R QW US. Patent Dec. 9 1975 Sheet4 of4 3,924,452

TRANS PULEEIZ &

C LOCK INVENTORS. EDWARD P. MEYER BY WILL/AM L. WQ/GHT WIQ/ G M n 4 WeATTOIENEYE.

SECTOR SCANNING ULTRASONIC INSPECTION APPARATUS This application is acontinuation of application Ser. No. 801,882, filed Oct. 1., 19 69,which application is a continuation-in-part of application Ser. No.373,312 filed June 8, 1964, now both abandoned.

The present invention uses ultrasonic techniques closely related to theecho-ranging techniques developed in the field of sonar during andafterWorld War II. Ultrasonic echo-ranging devices normally include agenerator for producing ultrasonic energy, a transducer for applyingvibrational energy toa medium of transmission and receiving energyechoed back through that medium, a receiver for amplifying and detectingthe echoed energy, an indicating unit for displaying the echoedinformation and a control (synchronizing) unit for synchronizing theaction between transmitter and receiver.

The present invention is also related to non-destructive testing (NDT),which is the inspection of the surface or interior of a solid objectwithout destroying the object. X-rays and gamma rays are also used incertain types of such testing, but such rays are electromagnetic andhence can penetrate only limited distances into metal.

Ultrasonic visualization techniques are being increasingly used fornon-destructive testing and in particular for medical diagnosis. Theapproach. used in medical diagnosis is basically similar to those usedin nondestructive testing and echo-ranging. The transducer is applied tothe area under investigation, pulses of ultrasonic energy are applied,and reflected pulses (echoes) are detected and displayed on a cathoderay tube.

Ultrasonic examinations are possible in areas where X-ray examinationsare either inconclusive or inadvisable, such as in examinations of thecranium and eyes. By studying the displayed data, the examiningphysician can distinguish between normal and abnormal tissues. Theseultrasonic techniques have been found useful in detecting cancers, andother tumore in the brain, breast and heart. For the study of organslike the liver, kidney, spleen, pancreas and breast, and for study offluid-filled structures like the bladder, stomach and pregnant uterus,ultrasonics will give pictorial anatomical and pathological informationnot obtainable by X- ray.

The apparatus and methods heretofore available have had some seriousdisadvantages principally in terms of resolution of the objects underobservation and the degree of skill required by the operators. Also, inthe past most ultrasonic equipment required that the object beinginvestigated be placed in a fluid bath during actual investigation.

It is an important object of the present invention to provide animproved arrangement for the utilization of ultrasonic energy innon-destructive testing and a method of using it which overcomes some orall of the disadvantages of prior art devices.

Another important object of the present invention is to provide forimproved scanning of the object under investigation to provide greaterresolution.

A further object of the present invention is to avoid the necessity ofimmersion of the object during the investigation procedure.

A still further object of the present invention is to provide animproved scanning arrangement which automatically relates thepositioning of the ultrasonic transmitter and receiver with the imageproduced on a read-out device, such as a cathode ray tube.

Still another object of the present invention is to provide a scanner ofimproved design for use with apparatus utilizing ultrasonic principleswhich permits rocking the transducer to provide improved resolution ofinternal aspects of a solid body.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a side elevational view of the scanner portion of ultrasonicequipment constructed in accordance with the principles of the presentinvention;

FIG. 2 is a top view of the structure illustrated in FIG. 1 taken inplanes substantially indicated by lines 2-2;

FIG. 3 is a rear elevational view of the equipment illustrated in FIG.1;

FIG. 4 is a transverse sectional view of the structure illustrated inFIG. 1 taken along the lines 4-4;

FIG. 5 is a side elevational view of a single one of the pulleysillustrated in FIG. 1;

FIG. 6 is a top view of the pulley illustrated in FIG. 5;

FIG.. 7 is a diagrammatic top view of the linkage system with certainportions cut away to show the outermost connection of the apparatus withthe potentiometers;

FIG. 8 is a mechanical diagrammatic view of the ultrasonic apparatusillustrated in FIG. 1;

FIG. 9 is a schematic diagram of one embodiment of electric circuitry ofthe apparatus;

FIGS. 10A and 10B illustrate respectively a typical method of prior artscanning and that of the present invention;

FIG. 11 is another mechanical diagrammatic view of the ultrasonicapparatus shown in FIG. 1, but showing additional definable quantities;and

FIG. 12 is a schematic diagram of another embodiment of electroniccircuitry of the apparatus that takes into account the additionalquantities shown in FIG. 11.

Inaccordance with the present invention, there is provided apparatusincluding a transducer for sending ultrasonic signals through an objectunder investigation and for receiving signals reflected back thereto,and a device for translating the reflected signals into a suitablereproduction of the object being investigated. The apparatus includes ascanning arrangement, which comprises a base having a support mountedthereon for pivotal movement, a series of arms successively andadjustably connected to each other having one end of the first of thesuccessively connected arms mounted on the support and having anultrasonic transducer mounted at the end of the last of the successivelyand adjustably connected arms. A series of potentiometers areoperatively connected to the adjustable arms upon which the transduceris mounted, the potentiometers being adapted to develop signalsrepresentative of the positioning of the arms. Means are provided fortransmitting the developed signals to the translating device fortranslating the position and attitude of the source of ultrasonicsignals into a suitable reproduction which is properly oriented withrespect to the object being investigated.

With reference to the drawing and, in particular, to FIGS. 1, 2, 3 and4, a system embodying the invention includesa frame 10, having its rearsurface mounted on a rear vertical element 12 of a support 14 providedwith feet 15, which may be optional. A screw wheel 16 is threaded onto abolt 17 which passes through the upper portion of the rear verticalelement 12 and is attached to the frame to permit positioning of theframe 10 in any desired angular position about the axis of the bolt 17.A center plate 18 is mounted interiorly of the frame 10 on mounting lugs20. Positioned on the center plate 18, one above the other, are threesine-cosine potentiometers indicated generally from bottom to top as 22,24 and 26. The slider of each potentiometer is operatively coupledthrough a mechanical linkage to a transducer 32 to provide electricalsignals representative of the position of the transducer as will belater described.

A pair of spaced parallel arms 28 extend horizontally from the front ofthe frame 10 and are mounted thereon at one end by bolts 29. The armsare held in spaced-apart relation by spacers 30 and studs 31. Anelectrical plug connection 13 is located on the back of the frame 10through which electrical power is supplied generally to the device, andthrough which ultrasonic signals are supplied to and taken from thetransducer 32. The frame 10 may be selectively positioned about ahorizontal axis passing through the bolt 17 by loosening the screw wheel16, repositioning the frame and tightening the screw wheel.

The system by which the movement of the transducer 32 is translated intoelectrical signals will now be described. Referring particularly toFIGS. 1 and 8, it will be noted that the system contains threeinterconnected arms 34, 36 and 40. The first arm 34 is bifurcated ateach end, with one bifurcated end pivotally connected to the arms 28 bymeans of a shaft 37. The other bifurcated end of the first arm 34 issimilarly pivotally connected to a bifurcated end of the second arm 36by means of a shaft 39. The other end of the second arm 36 is alsobifurcated and pivotally attached to a similarly bifurcated end of thethird arm 40 by means of a shaft 43. The transducer 32 is attached tothe opposite end of the third arm 40 by a screw connector 44, whichincludes a plug and socket for electrical connections (not shown). It isnow readily seen that the first arm 34 pivots about the axis of theshaft 37. The second arm 36 being pivoted to the first arm 34 and thethird arm 40 being pivoted to the second arm 36 permits the transducerto describe almost a complete circle. The pivotal connections of thefirst and second arms 34 and 36 respectively permit the positioning ofthe end of the second arm at almost any point within a plane normal tothe axes of the shafts 37, 39, 43. The third arm 40 being pivoted to thesecond arm 36 in effect may pivot about any point in a plane limitedonly by the total motion of the first arm 34 and the second arm 36. Thethird arm 40 permits freedom of angular position of the transducer 32allowing the transducer 32 to be placed at any position in the plane andits axis aligned at any angle within its limits. Furthermore, since theframe 10 can be rotated about a horizontal axis at right angles to theaxes of the pivoting arms 34, 36 and 40, the inspection plane can beadjusted substantially to any desired angle.

The transducer 32 in being positioned to scan the object or individualunder investigation moves the sliders of the potentiometers 22, 24 and26 mounted on the frame 10 to correspond to such positioning. Thepotentiometers translate the movement of i the transducer intoelectrical signals which are applied to a readout device, such as acathode ray tube (CRT), for displaying the desired internal structure ofthe subject uncle: investigation upon the screen of the tube.

Referring now to FIGS. 4, 5 and 6, it will be seen that thepotentiometers 22, 24 and 26, which are of the sine-cosine type, aremounted on the center plate 18 of the frame 10 one above the other. Thepotentiometers 22, 24, 26 have sliders respectively mounted on shafts35, 38, 42, which are adapted to be adjusted in such a manner'as toprovide signals on the sliders that correspond to trigonometricfunctions of the respective angles formed between the arms 34, 36 and 40and the horizontal. The potentiometer shafts extend through openings inthe plate 18. The shafts 35, 38, 42 respectively have pulleys 47, 62 and49 securely mounted thereon and held in position by screws 25, 63 and 57respectively.

Again referring to the drawings in general but, in particular, to FIGS.1, 2 and 7, the structure and operations relative to the manner ofactuating the potentiometers and producing a suitable reproduction ofthe object under investigation will now be discussed. It is seen that apulley 48 is pivotally mounted on the shaft 37 at the pivotal positionof arm 34 and within the bifurcations of arm 34 and the parallel arms28. The pulley 48 is fixedly connected to the arm 34 by pin or screw 50and rotates with the arm 34 about the shaft 37. A belt 46, which maytake the form of a steel wire, is passed around each of the pulleys 47,48, thus providing a driving connection between the potentiometer 22 andthe arm; 34 in such a manner as to allow a proportional rotation betweenthe potentiometer 22 and the arm 34, which may conveniently have aone-to-one relation. Screws 66 and 68 provided near the periphery of thepulley 48 receive the ends of the belt 46 in a manner to permit thetensioning of the belt 46 over the pulleys. Thus it is seen that thepotentiometer 22 is mechanically coupled through the pulleys 47 and 48,the belt 46, and the screw 50 to the arm 34.

The potentiometer 26 has a pulley 49 attached to its shaft 42 by a screw57 and is driven by a belt and pulley arrangement in a manner to bemechanically coupled to the arm 36. The potentiometer 26 is connected tothe arm 36 through a belt 51 which passes around the pulley 49 over asecond pulley 52 which acts as an idler pulley mounted for free rotationon the shaft 37. The pulley 52 is not directly connected with the firstarm 34 and does not rotate with movement of that arm. The belt 51 isextended to be connected to a pulley 54 mounted on the shaft 39 andfixedly connected to the arm 36 by a pin or screw 61. Since the pulley54 is directly connected to the arm 36, movement of the arm 36 about theaxis of the shaft 39 is, of course, transmitted through the belt 51, theidler pulley 52 and the pulley 49 to the shaft 42 of the potentiometer26, but no motion of the potentiometer shaft 42 will occur as a directresult of movement of the arm 34. Screws 74 and 76 are provided on thepulley 49 to provide for tensioning and holding the belt 51.

.The third potentiometer 24 is arranged to be responsive to'angularmovement of the third or transducer arm 40. Anidler pulley 56 is mountedfor free rotation on the shaft 37 in the same manner as the pulley 52.Another idler pulley 58 is similarly mounted for free rotation on theshaft 39. A pulley 60 is mounted on the shaft 43 and is directlyconnected to the third arm 40 by a pin or screw 60'. The pulley 60 isadapted to rotate with the third arm 40 about the axis of the shaft 43.A pulley 62 is mounted on the potentiometer shaft 38 and held by screws63. A belt 64 is passed around each of the pulleys 56, 58, 60, 62 in aconventional manner to provide a driving connection between the thirdarm 40 and the shaft 38 of the potentiometer 24. The belt 64 may beconveniently arranged to pass continuously over the four pulleys byusing additional turns as necessary at each pulley. Since the pulley 60is directly connected to the transducer arm 40, angular movement of thearm 40 about the axis defined by the shaft 43 is transmitted to theshaft 38 of the potentiometer 24. Thus, it is apparent that uponvariation of the positions of the arms 34, 36, and 40, the involved beltand pulley arrangements will cause the positions of sliders of the threepotentiometers 22, 24, 26 to be varied to correspond with the angularpositions of the respective arms.

In order to better understand the operation of applicants invention,attention is further directed to FIG. 9, which is a partially block andpartially schematic diagram of the electrical circuitry of apparatusembodying the invention. As is well-known in the art, ultrasonic wavesmay be appropriately generated by driving a transducer by applying thereto an electrical signal hav ing a frequency in the ultrasonic range. Thetransducer normally includes a transducer element which may be composedof barium titanate or lithium sulfate. However, it may be also composedof other materials displaying piezoelectric or magnetostrictivecharacteristics. The ultrasonic energy waves generated are then beamedinto the object under investigation. When the ultrasonic waves contactareas of varying density within the investigated object, echoes arereflected back from the interfaces to the transducer where they generateelectrical signals. The signal directed into the object underinvestigation and reflected back to the transducer from surfaces andinterfaces may be applied to the Z axis input of an oscilloscope tomodulate the electron beam intensity and produce a visible pattern ofthe echo signals received imposed on a time base or sweep. The speed ofthe sweep is generally one-half that of the ultrasonic wave in the bodybeing examined to take into account the time of travel to and from anechoproducing density variation and thus produce a full distance scalerepresentation on the face of the oscilloscope. When the transducer ispositioned against the surface of the object under investigation, thesignal applied thereto from the generator is immediately reflected fromthat surface, thus identifying the position of the transducer and thepoint of origin of the trace on the readout device. As echoes arereceived and displayed, the relative positioning is also established. Byusing a cathode ray tube having a long time-persistence phospher, thesesignals will remain for a period of time sufficient to permit theproduction of a permanent pho tographic record or, if desire, they canbe fed to a storage tube or the like for future reference.

lt has been found that markedly increased resolution of the internalstructure of a body is obtained when the beam of ultrasonic energy isinjected into the body from a source located at the surface of the bodyand the beam is pivoted about its point of introduction to cover anangular field or sector within the body. Multiple sector scans of thebody are obtained by scanning from several points on the body surface.The present invention relates to a method of multiple sector scanning ofa body under investigation using ultrasonic techniques and withapparatus for practicing the method.

To facilitate ease of use, the transducer or transmitter needs to havewide latitude of movement. lndications of this movement needs to beimpressed on a readout device to permit the operator at all times to beable to correlate the position of the transducer or source of theultrasonic energy beam with the position of the image or data appearingon the readout device. To facilitate the description of the system inaccordance with the present invention that accomplishes that result,reference is made to FIG. 8, which schematically represents the pivotedsuspension system of FIG. 1. As previously indicated, the two arms 34,36 are respectively mechanically coupled to the potentiometers 22, 26,which potentiometers serve to provide signals indicative of the locationof the pivot point of arm 40 (the shaft 43) with respect to the fixedpivot point defined by the shaft 37.

To locate the shaft 43, reference axes X and Y are chosen that passthrough the axis of the shaft 43. The coordinates of the position of theaxis of the shaft 43 are (algebraically):

x x, X l where x L, cosa Thus,

x L cosoz L 6080:; (2) where The potentiometers 22, 26 and 24 are eachof a wellknown type that provides two electrical output signals whoseamplitudes correspond to sine and cosine trigonometric functions of therotational position of the shaft of the potentiometer. A suitablepotentiometer is known as a Model 303, available from Computerlnstruments Corporation, Hempstead, NY. With the arrangement shown, ifequal positive and negative voltages are applied across a potentiometer,then the output may change polarity from positive to negative as theangle of the shaft changes. Thus, if +E,,, and E,,, volts are appliedacross the potentiometer 22, the sine and cosine outputs from thesliders 22a and 22b, respectively are E, out E, sina,

and

E, out E cosa,

where a, is the angle of rotation of the shaft connecting the twosliders 22a, 22b with respect to the reference position, which is thesame as the angle 0:, shown in FIG. 8. A corresponding relationshipexists for the potentiometer 26 and its sliders 26a, 26b with respect tothe angle a When the corresponding arm 34, 36, 40 controlling apotentiometer 22, 26, 24 is horizontally extended, the output from thesine slider a is zero, and the output from the cosine slider b ismaximum positive; when the corresponding arm is turned horizontallyinwardly, the a output is again zero, and the b output is maximumnegative. Both the sine and cosine functions are thus obtainable fromtwo sliders of each potentiometer, or

nay be obtainable by other means as known in the art.

To provide for the proper voltage output ratio from he potentiometers 22and 26 in terms of positions of he axes of the shafts 39, 43, thevoltages impressed Cross the potentiometers 22 and 26 are in the sameatio as the respective lengths ofthe arms 34 and 36, or

"hus, conversion means are provided for converting he positions of theaxes of the shafts from polar to rect ngular coordinates.

Now the position of the shaft 43 with respect to the x, axes may beobtained in accordance with the relationhip E out=E, out+E,. out (8) E,out E, out E out (9) /here E out KX E out Ky nd constant K hasdimensions of volts per unit length. Again referring to FIG. 9 the -E,,out and E out voltges from the sine function sliders 22a, 26a of thepoantiometers 22, 26 are fed to a Y adder 70 and the sum utput of theadder 70 is fed to a vertical deflection amlifier 72 for drivingvertical deflection plates of a cathde ray tube 74. In like manner, theE, out and E out oltages from sliders 22b, 26b of the potentiometers 22,6 are fed to an X adder 76 and the sum output of the dder 76 is fed to ahorizontal deflection amplifier 78 )r driving horizontal deflectionplates of the cathode ay tube 74. These voltages establish the origin ofthe can of the electron beam on the face of the tube and, y adjustmentof positioning controls of the oscillozope, the spot can be positionedas desired at any oint or off the face of the tube. The spot may not beisible as the beam may be biased to cut-off to be visile only when asignal of the correct polarity is applied a Z axis or intensity controlelectrode 92 of the cathde ray tube 74.

The potentiometer 24, which is coupled to and actuted by the movement ofthe arm 40 carrying the transucer 32, provides electrical signalsrepresentative of ie angular positioning of the arm 40 with respect to1e horizontal. Thus, the angle made by the arm 40 de- :rmines also thedirection of the beam of ultrasonic nergy provided from the transducer32. A signal is deeloped at a slider 24a of the potentiometer 24 whichis :presentative of the sine function of the angle (1 (FIG. with respectto the horizontal, which signal is fed to ie sweep generator 80. Thesweep generator 80, upon :ceiving a pulse on a trigger input 81,develops an outut, usually of the sawtooth type, the time rate of riseof hich is governed by the amplitude of the signal from 1e sine functionslider 24a. In a similar manner, a sigal is developed at a slider 24b,which is representative fthe cosine function of the angle 01;, withrespect to re horizontal. This signal is fed to a sweep generator 2,which develops a sawtooth output signal in re- )onse to a signal on itstrigger input 83. The time rate frise of the sawtooth signal is governedby the amplilde of the signal from the cosine function slider 24b.

The output signal from the sweep generator is fed to the verticaldeflection amplifier 72, and the output from the sweep generator 82 isfed to the horizontal deflection amplifier 78. The combined outputs fromthe sweep generators 80 and 82 cause the electron beam to be sweptacross the face of the cathode ray tube 74 and the direction that thepath of movement of the electron beam takes is correlated to, andcontrolled by, the angle 01;, of the arm 40.

The sweep generators 80, 82 are triggered by a pulse from a clockgenerator 84 to start the sweep of the cathode ray tube electron beam.This same pulse is fed to a pulser 88 through delay means 86. The timedelay provided by the delay means 86 is sufficient to permit the CRTelectron beam to travel a distance equivalent to the distance from theradiating surface of the transducer 32 to the shaft 43 before thetransducer is energized, so that the apparent origin of the sweeprepresents the true position of the shaft 43. This delay is requiredonly where the transducer is in fact displaced from the known positionof shaft 43. The transducer 32 is energized by the pulser 88 producing apulse of ultrasonic energy. The output of the pulser 88 is also fed tothe intensity control electrode 92 of the cathode ray tube through anamplifier 90.

It will be seen that the scale or image size will be a function of themagnitude of the deflection voltages applied to the deflection plates ofthe cathode ray tube 74. By adjusting the voltages applied to thepotentiometer 24 by means of a rheostat 94 or other suitable means, thescale of the image may be selected. The scale or size of the image mayalso be changed by maintaining the input voltage to the potentiometer 24constant and varying the gain of the deflection amplifiers 72 and 78 aswill be understood by those skilled in the art.

In operating the device, the generating surface of the transducer ispositioned against the surface of an object under investigation. Eachtime a clock pulse from the clock 84 reaches the sweep generators, sweepsignals of suitable wave forms are produced and applied to thedeflection means of the cathode ray tube in accordance with the signalsreceived from potentiometer 24, which reflect the angle a that the arm40 makes with the horizontal. Thus, the electron beam starts to scanacross the face of the tube, although it is invisible to the eye. Thescan originates at a point which corresponds to the position of theshaft 43 and moves in a direction which corresponds to the angularposition of the arm 40; that is, in the direction the ultrasonic beamfrom transducer 32 is directed. The clock pulse from the clock 84 isalso applied to the delay means 86. The clock pulse from the clock 84 isalso applied to the delay means 86. After the electron beam has traveleda distance equivalent to the length of the arm40, the pulser 88 isenergized which pulses the transducer 32. The output of the pulser 88 isalso amplified by the amplifier 90 and applied to the intensity controlelectrode of the cathode ray tube and appears on the face thereof as aspot of visible light. The beam of ultrasonic energy is propagatedwithin the body under investigation, and when the beam encounters achange in density within the body, a reflection wave or echo isreflected back to the transducer 32. As a reflection is received, it isamplified by the amplifier 90 and applied to the intensity coontrolelectrode 92 of the cathode ray tube so that it apperas on the CRT faceas a visible spot of light. In the time interval between the originalsignal generated by the transducer 32 and the reflected signal received,the CRT electron beam will have moved across the face of the tube sothat spots representing reflections will occur in spaced relationcorresponding to the distance from the surface of the object and theinternal anomaly, and in a direction essentially corresponding with theaxis of the ultrasonic beam. The repetition rate of the clock 84 ischosen to permit the receipt and storage of the echo signals from aparticular object before the generation of a new signal.

With the system of the present invention, it is possible to carry out asector scanning of an object from essentially any position and in anyplane. Referring to FIGS. A and 10B, FIG. 10A depicts the manner inwhich prior art scanning has been carried out. First, a transducer 96and an object 98 under investigation are separated usually by water andthe transducer is traversed in a straight line manner. A defect 99within the object 98 is displayed usually upon a cathode ray tube orstorage tube. The image has generally had poor resolution. In contrastthereto, the transducer 32 of the present invention is close to theobject under investigation (FIG. 10B) and is rocked essentially about apoint on the surface of the object. For reasons not yet completelyclear, the resolution of an image of a defect 99 in a body 98 ismarkedly improved over the results obtained with the prior artteachings. It is theorized that the manner of scanning provides greaterimpingement of waves on the defect, and the device of the inventionprovides ready access to the information obtained from a body underinvestigation.

FIGS. 11 and 12 illustrate a modification of the invention, whereby itis possible to locate the position of the transducer 32 exactly in termsof the reference axes X and Y. Thus, the delay 86 shown in FIG. 9 can beeliminated.

Referring now to FIG. 11, it is seen that if L and a are known, then X,L; com, (10) X and Y axes becomes and Y Y Y, Y, L, sina, sina, L, sina,

Signals proportionalto the sine and cosine functions of the angles a a01,, are respectively obtained from the potentiometers 22, 26, 24 aspreviously described.

FIG. 12 illustrates one form of electronic circuitry for accuratelypositioning origin of the sweep of the beam of the cathode ray tube 74at a point corresponding to the location of the emitting surface S ofthe ultrasonic transducer 32. The cathode ray tube beam is then causedto sweep at an angle, as previously described, dictated by the angle a,representative of the angular positioning of the third or outermost arm40 that carries the transducer 32.

The embodiment of the invention shown in FIG. 12 differs from that shownin FIG. 9 in that the potentiometers 22, 24, 26 are not energized byvoltages that are proportional to the lengths of the arms 34, 40, 36.Rather, the potentiometers are all energized from the same equalpositive and negative voltage sources +E and E,,,. The X and Y componentvoltages from the potentiometers are provided separately to passiveresistor adder networks as shown in FIG. 12.

Looking first at the Y component positioning and sweep channel, it isseen that the signal representing sin X is provided from the slider 22aof the potentiometer 22 to one end of a resistor y. Similarly, a signalrepresenting sinoz is provided from the slider 26a to one end of aresistor 102y, and a signal proportional to sinoz is provided from theslider 24a to a resistor 104y. The other ends of the resistors l00y,102y, l04y are connected together and to an input of an operationalamplifier 106y. Also connected to the input of the amplifier 106y is oneend of a resistor 108y, whose other end is connected to a slider of apotentiometer 1l0y. The potentiometer l10y is connected between positiveand negative voltages +E and *E, and the voltage taken from its movablearm serves as a Y position centering control for the start of the sweepon the cathode ray tube 74.

The output of the operational amplifier 106y is connected through anelectronic switch ll2y to an input of another operational amplifierll4y. The latter amplifier is part of a sweep generator to provide forvertical or Y deflection of the cathode ray tube beam. To this end, theoutput of the amplifier ll4y is connected to the vertical deflectionamplifier 72 to provide positioning and sweep voltages of the properamplitudes for the cathode ray tube.

A feedback resistor 1 16y connects the output of the amplifier ll4y tothe input of the amplifier 106y. An integrating capacitor 118y'isconnected directly across the amplifier 1l4y. A resistor y is connectedfrom the juncture of the switch ll-2y and the amplifier 1l4y to the arm24a that provides a signal proportional to sinu The capacitor 118 andthe resistor l20y, acting in conjunction with the switch l12y and theamplifier 114y, provide the vertical or Y axis sweep for the cathode raytube beam.

It is pointed out that the values of the resistors 100y, 102y, l04y arerespectively inversely proportional to the lengths of the arms L L LThis feature provides the conversion means necessary so that the inputvoltages to the amplifier 106y are proportional to X and Y positioncoordinates. Thus, the voltages supplied to the input of the operationalamplifier 106y from the adder network are proportional to Y, Y Y plus avoltage from the potentiometer ll0y that is used for centering purposes.These voltages are modified by the voltage developed across thelfeedbackresistor ll6y. The voltage provided from the-amplifier 106y throough theswitch 112y to the amplifier l14y is proportional to the Y axis positionof the point S on the emitting face of the transducer 32.

While the signal provided from the amplifier 106y determines the originof the cathode ray tube beam sweep, the signal from the potentiometerarm 24a and the time constant of the capacitor 118y and the resistor120y determine the vertical sweep speed. The output of the amplifierl14y is a linear ramp (sawtooth) voltage, whose slope is proportional tothe sine of a a, is, of course, the angle that the arm 40 carrying thetransducer makes with the horizontal.

The fundamental purpose of the switch l12y is to position the cathoderay tube beam at the proper coordinate in the Y direction prior to thestart of the sweep. The switch 112y, which is a conventional electronicswitch, is opened and closed by pulses received from the clock generator84. When a pulse is received from the clock generator 84, the switchll2y is closed, so that the output positioning voltages of the amplifierl06y are provided as input voltages to the amplifier ll4y. Thisinitially positions the beam of the cathode ray tube at the proper Ycoordinate to start the sweep. At the end of the clock pulse, the switchl 12y opens and generation of the sawtooth sweep voltage is initiated.This continues until receipt of another clock pulse from the generator84, at which time the starting point of the sweep in the Y- direction isre-positioned if the transducer 32 has been moved in the interim.

The X or horizontal deflection channel comprises components that areidentical to those in the Y or vertical channel. Correspondingcomponents in the horizontal channel are identified bythe same referencenumerals as thosein the vertical channel, but are followed by a suffix xrather than y. The only difference between the two channels is .t hattheinput signals to the adder network of the x channel are taken from thecosine slid.- ers 22b, 24b, 26bi-of the three.pote n-tiorne ters ratherthan from the sine sliders. ltis believedthat adetailed explanation ofthe constructionand operation o fthechannel is not necessary to at'ullnderstanding ofthe invention, in view of the description, ot-,tlge, y,channel. The composite output voltage of thetverticaldeflcc; tionamplifier 72 corresponding to the Y,pos itiqn of the transducer surfaceS and the sine of the angleq and the composite voltage from thehorizontal deflection amplifier 78 representing the. X position of thetransducer face S and the. cosine of the angle .0 are added vectoriallyin the electrostatic deflection cathode ray tube 74. This produces atrace on the cathode ray tube face which corresponds completely inposition and direction to the path of the ultrasonic beam produced bythe transistor 32 in an object under investigation.

Although the invention has been described with a certain degree ofparticularity, it will be understood that the present disclosure hasbeen made only-by way ofexample and that numerous changes in the detailsof construction andthe combination and arrangement of parts may beresorted to without departing from the spirit and scopeof the inventionas hereinafter claimed. We claim: 1. In an ultrasonic apparatus forinvestigating the internal structure of an object and having anelectroacoustic transducer for transmitting a beam of ultrasonicacoustic signals through an object to be investigated and for receivingultrasonic acoustic signals rea. supporting means supporting theelectroacoustic .transducer form ovement limited within apredeterminedplane ;while, in contact with the surface of said object, said:supporting means comprising i. a base and I ii. first, second and thirdarms successively and pivotally connected one to another on first andsecond pivotal axes, respectively, and to said base on a third pivotalaxis for movement within said Single plane' normal to saidelectroacoustic transv -jducer{ being rnounted at an end of said firstof r said;,succes sively[connected arms most remote fr m ai base;

b. -first sine/cosine resolver means mounted on said base andoperatively connected to said first arm for providing first electricalsignals corresponding to direction ofemission of said ultrasonic beam;

c. second and third; sine/cosine revolver means mounted on said base andrespectively operatively connected.tosaidsecond and third arms forrespectively providing second and third electrical signals respectivelyrelated to angular positions of said l first andsecond axes about saidsecond and third I ,axes, respectively 7 v d.. conversion means forrespectively converting said second, and third electrical signals intofourth and ordinates of positions of said first and second axes; e.means for algebraically combining said fourth and I fifth electricalsignals to provide sixth electrical signals proportional to X and Yco-ordinates of positionofoneend of saidjfirst arm; and

means for transmittingsaid sixth electrical signals .to saiddeflection-means fogv arying origin of said M readoutindicator tocorrespondto location of said .1, One end-of saidfi rst arrii and'fortransmitting said first electrical,signals to. saiddeflection means forcontrolling direction offd eflecti on of said readout indicatortocorrespond to direction of emission of 'said'beam of ultrasonic energyfrom said transducer in .saiclpredetermined plane.

The combination of claim}, wherein said first,.sec-

fond andthird resolver means e'ach c ornprise a potentiomet'e'r havingtwo outpiifslide'rs controlled by a rotatableshaft for respectivelyproviding signals to two trigonometric functions of rotational positionof said shaft.

3. The" combination of claim 1, wherein said base is rotatable about afourth axis to vary angular position of said predetermined plane.

4. The combination of claim 2, wherein said base is rotatable about afourth axis to vary angular position of said predetermined plane.

5. The combination of'claim 2, wherein said first, second and third armsare/respectively connected to said rotatable shafts of said first,second and third resolvers by means of individual belt and" pulleyarrangements.

6. The combination of claim 5, wherein said display device comprises acathode ray tube.

7. The combination of claim 5, wherein said conversion means includesmeans for respectively energizing said second and third resolver meanswith voltages re: spectively proportional lengths of said second andthird armsl;

8. The combination of claim 5, wherei'n said first, second and thirdaxes are parallel to each 'other and normal to said fourth axis. v

v 9. A method of ultrasonically examining the internal structure of anobject to' provide improved resolution .wit h anelectroaconstictransdncer mounted on the end of aseriesofpivotally'interednnected arms comprising .the' teps of? p a.positioning said transducer'against said object to be:investigated; '3-

f b. moving saidarms wit "1 -a"single plane while pivoting the saidtransducerin a rocking movement in said singleeplane substantially abouta single point onthe-sarfaee of said" ject in the area thereof to fifthelectrical signalsproportional to X and Y 00- 13 be investigated;

c. transmitting ultrasonic signals from the said transducer into saidobject and receiving by means of said transducer ultrasonic signalsreflected by internal structure of said object;

d. developing electrical signals representative of the positioning ofsaid arms and said transducer; and,

e. producing a visual representation of the ultrasonic reflections andcontrolling the origin and direction of the visual representationproduction to correspond to location of the transducer and direction oftransmission of the ultrasonic signals to provide a reproduction of theinvestigated object which is oriented with respect to the object.

10. In an ultrasonic apparatus for investigating the internal structureof an object and having an electro acoustic transducer for transmittingultrasonic acoustic signals through an object to be investigated and forreceiving ultrasonic acoustic signals reflected back thereto, anultrasonic generator connected to said transducer, a readout device fortranslating reflected acoustic signals received by said transducer intoa visible reproduction of reflections from and within said object beinginvestigated, said readout device comprising a display device having areadout indicator and deflection means for deflecting said indicatoralong X and Y axes, the combination comprising:

a. supporting means supporting the electroacoustic transducer forrestraining movement of the transducer to a single predetermined planewhile in contact with the surface of said object, said supporting meanscomprising i. a base,

ii. a first arm pivotally connected to said base for movement only abouta first axis perpendicular to a said predetermined plane, v

iii. a second arm pivotally connected to said first arm for movementonly about a second axis perpendicular to a said predetermined planeand,

iv. a third arm pivotally connected to said second arm for movement onlyabout a third axis perpendicular to a said predetermined plane, thetransducer being mounted on said third arm for transmitting andreceiving acoustic signals in a direction generally parallel to a saidpredetermined plane,

b. first resolver means mounted on said base and operatively connectedto said third arm for providing 14 first electrical signalscorresponding to direction of emission of said ultrasonic beam;

0. second and third resolver means mounted on said base and respectivelyoperatively connected to said second and first arms for respectivelyproviding second and third electrical signals respectively related toangular positions of said third and second axes about said second andfirst axes, respectively;

d. conversion means for respectively converting said second and thirdelectrical signals into fourth and fifth electrical signals proportionalto X and Y coordinates of positions of said first and second axes;

e. means for algebraically combining said fourth and fifth electricalsignals to provide sixth electrical signals proportional to X and Ycoordinates of position of said transducer; and,

f. means for transmitting said sixth electrical signals to saiddeflection means for varying the origin of said readout indicator tocorrespond to the location of said transducer and for transmitting saidfirst electrical signals to said deflection means for controlling thedirection of deflection of said readout indicator to correspond to thedirection of emission of said ultrasonic signals from said transducer insaid predetermined plane.

11. An apparatus as defined in claim 10 wherein said first, second andthird resolver means each comprise a sine/cosine potentiometer havingtwo output sliders controlled by a rotatable shaft for respectivelyproviding signals related to two trigonometric functions of rotationalposition of said shaft.

12. An apparatus as defined in claim 11 wherein said base is rotatableabout a fourth axis to vary angular position of said predeterminedplane.

13. An apparatus as defined in claim 12, wherein said first, second andthird arms are respectively connected to said rotatable shafts of saidfirst, second and third resolvers by means of individual belt and pulleyarrangements. 3

14. An apparatus as defined in claim 13 wherein said conversion meansincludes means for respectively energizing said first and secondresolver means with voltages respectively proportional to lengths ofsaid first and second arms.

15. An apparatus as defined in claim 14 wherein said first, second andthird axes are parallel to each other and normal to said fourth axis.

UNITED STATES PATENT AND TRADEMARK OFFICE EEEEATE 0F CORREETION PATENTN0. 3,924,452

DATED December 9, 1975 INVENTOR(S) Edward P. Meyer and William L. WrightIt is certified that error appears in the abuve-identified patent andthat said Letters Patent are hereby corrected as shown below:

In [63] on cover page, line 1, "October 1, 1969" should be October 1,1968 Col, 1, line 41, "tumore" should be tumors Col, 4, line 30, after"arm" delete Col, 5, line 54, "desire" should be desired Col 6, Equation(5), after"E insert in Col, 6, Equation (6) after "E insert in Col. 7,Equation (7) after "E and after "E insert in Col. 8, line 65, "coon-"should be con- Col, 8, line 67, "eras" should be ears Col. 9, Equation(13) before sin x insert L Col. 10, line 52, "throough" should bethrough Claim 1, paragraph c) "revolver" should be resolver Signed andScaled this eighth Day of June1976 asset! fittest:

RU'E'li CJIASON QMARSHALL DANN Arresting Offidr Commissioner of Patentsand Trademarks

1. In an ultrasonic apparatus for investigating the internal structureof an object and having an electroacoustic transducer for transmitting abeam of ultrasonic acoustic signals through an object to be investigatedand for receiving ultrasonic acoustic signals reflected back thereto, asource of ultrasonic electrical signals connected to said transducer, areadout device for translating reflected acoustic sIgnals received bysaid transducer into a visible reproduction of reflections from andwithin said object being investigated, said readout device comprising adisplay device having a readout indicator and deflection means fordeflecting said indicator along X and Y axes, the combinationcomprising: a. supporting means supporting the electroacoustictransducer for movement limited within a predetermined plane while incontact with the surface of said object, said supporting meanscomprising i. a base and ii. first, second and third arms successivelyand pivotally connected one to another on first and second pivotal axes,respectively, and to said base on a third pivotal axis for movementwithin said single plane normal to said electroacoustic transducer beingmounted at an end of said first of said successively connected arms mostremote from said base; b. first sine/cosine resolver means mounted onsaid base and operatively connected to said first arm for providingfirst electrical signals corresponding to direction of emission of saidultrasonic beam; c. second and third sine/cosine revolver means mountedon said base and respectively operatively connected to said second andthird arms for respectively providing second and third electricalsignals respectively related to angular positions of said first andsecond axes about said second and third axes, respectively; d.conversion means for respectively converting said second and thirdelectrical signals into fourth and fifth electrical signals proportionalto X and Y coordinates of positions of said first and second axes; e.means for algebraically combining said fourth and fifth electricalsignals to provide sixth electrical signals proportional to X and Yco-ordinates of position of one end of said first arm; and f. means fortransmitting said sixth electrical signals to said deflection means forvarying origin of said readout indicator to correspond to location ofsaid one end of said first arm and for transmitting said firstelectrical signals to said deflection means for controlling direction ofdeflection of said readout indicator to correspond to direction ofemission of said beam of ultrasonic energy from said transducer in saidpredetermined plane.
 2. The combination of claim 1, wherein said first,second and third resolver means each comprise a potentiometer having twooutput sliders controlled by a rotatable shaft for respectivelyproviding signals to two trigonometric functions of rotational positionof said shaft.
 3. The combination of claim 1, wherein said base isrotatable about a fourth axis to vary angular position of saidpredetermined plane.
 4. The combination of claim 2, wherein said base isrotatable about a fourth axis to vary angular position of saidpredetermined plane.
 5. The combination of claim 2, wherein said first,second and third arms are respectively connected to said rotatableshafts of said first, second and third resolvers by means of individualbelt and pulley arrangements.
 6. The combination of claim 5, whereinsaid display device comprises a cathode ray tube.
 7. The combination ofclaim 5, wherein said conversion means includes means for respectivelyenergizing said second and third resolver means with voltagesrespectively proportional to lengths of said second and third arms. 8.The combination of claim 5, wherein said first, second and third axesare parallel to each other and normal to said fourth axis.
 9. A methodof ultrasonically examining the internal structure of an object toprovide improved resolution with an electroacoustic transducer mountedon the end of a series of pivotally interconnected arms comprising thesteps of: a. positioning said transducer against said object to beinvestigated; b. moving said arms within a single plane while pivotingthe said transcucer in a rocking movement in said single planesubstantially about a single point on the surface of said object in tHearea thereof to be investigated; c. transmitting ultrasonic signals fromthe said transducer into said object and receiving by means of saidtransducer ultrasonic signals reflected by internal structure of saidobject; d. developing electrical signals representative of thepositioning of said arms and said transducer; and, e. producing a visualrepresentation of the ultrasonic reflections and controlling the originand direction of the visual representation production to correspond tolocation of the transducer and direction of transmission of theultrasonic signals to provide a reproduction of the investigated objectwhich is oriented with respect to the object.
 10. In an ultrasonicapparatus for investigating the internal structure of an object andhaving an electroacoustic transducer for transmitting ultrasonicacoustic signals through an object to be investigated and for receivingultrasonic acoustic signals reflected back thereto, an ultrasonicgenerator connected to said transducer, a readout device for translatingreflected acoustic signals received by said transducer into a visiblereproduction of reflections from and within said object beinginvestigated, said readout device comprising a display device having areadout indicator and deflection means for deflecting said indicatoralong X and Y axes, the combination comprising: a. supporting meanssupporting the electroacoustic transducer for restraining movement ofthe transducer to a single predetermined plane while in contact with thesurface of said object, said supporting means comprising i. a base, ii.a first arm pivotally connected to said base for movement only about afirst axis perpendicular to a said predetermined plane, iii. a secondarm pivotally connected to said first arm for movement only about asecond axis perpendicular to a said predetermined plane and, iv. a thirdarm pivotally connected to said second arm for movement only about athird axis perpendicular to a said predetermined plane, the transducerbeing mounted on said third arm for transmitting and receiving acousticsignals in a direction generally parallel to a said predetermined plane,b. first resolver means mounted on said base and operatively connectedto said third arm for providing first electrical signals correspondingto direction of emission of said ultrasonic beam; c. second and thirdresolver means mounted on said base and respectively operativelyconnected to said second and first arms for respectively providingsecond and third electrical signals respectively related to angularpositions of said third and second axes about said second and firstaxes, respectively; d. conversion means for respectively converting saidsecond and third electrical signals into fourth and fifth electricalsignals proportional to X and Y coordinates of positions of said firstand second axes; e. means for algebraically combining said fourth andfifth electrical signals to provide sixth electrical signalsproportional to X and Y coordinates of position of said transducer; and,f. means for transmitting said sixth electrical signals to saiddeflection means for varying the origin of said readout indicator tocorrespond to the location of said transducer and for transmitting saidfirst electrical signals to said deflection means for controlling thedirection of deflection of said readout indicator to correspond to thedirection of emission of said ultrasonic signals from said transducer insaid predetermined plane.
 11. An apparatus as defined in claim 10wherein said first, second and third resolver means each comprise asine/cosine potentiometer having two output sliders controlled by arotatable shaft for respectively providing signals related to twotrigonometric functions of rotational position of said shaft.
 12. Anapparatus as defined in claim 11 wherein said base is rotatable about afourth axis to vary angular position of said predetermined plane.
 13. AnApparatus as defined in claim 12, wherein said first, second and thirdarms are respectively connected to said rotatable shafts of said first,second and third resolvers by means of individual belt and pulleyarrangements.
 14. An apparatus as defined in claim 13 wherein saidconversion means includes means for respectively energizing said firstand second resolver means with voltages respectively proportional tolengths of said first and second arms.
 15. An apparatus as defined inclaim 14 wherein said first, second and third axes are parallel to eachother and normal to said fourth axis.